Normalizing hammer for dented sheet metal



Jan. 7, 1941. TOQP 2,227,949

NORMALIZING HAMMER FOR DENTED SHEET METAL Filed July 16, 1958 Fre de ric/f T 0 0 p.

Patented Jan. 7, 1941 PATENT OFFICE NORMALIZING HAMIHER- FOR. DENTED SHEET METAL Frederick Toop, York, Pa., assignor to Petco, Inc., York, Pa., a corporation of Delaware Application July 16, 1938, Serial No. 219,581

2 Claims.

This invention relates to a normalizing kit for dented sheet metal, also to certain units ofthe repair kit, including a rotary hammer and a multisided manipulative anvil.

While there are numerous uses to which the invention is applicable, its greatest current use may probably be found in repairing dented portions of automobile wheel-fenders or mud-guards, and less often, the hoods and body portions of automobiles.

One object of the invention is to meet the current need of a. very practical, efiicient and accurate means for hammering and pressing dents out of sheet-metal objects so as to restore the dented parts to normal shape, viz., to normal convexity and concavity with even and smooth sur- 1 faces, without indenting the metal and without the necessity for filing or otherwise abrading the affected parts preparatory to recoating, or without the necessity for recoating in many instances.

Another object is to attain the foregoing objects by application of comparatively light hammer-strokes in rapid succession while moving the hammer along the bulged side of the dented part to be normalized or restored to its normal and proper shape.

Another object is to provide, in alternate combination with a rotary spindle and its adjuncts, a plurality of rotary hammer-heads that are interchangeably attachable to said spindle, and which are of various shapes so as to meet the various requirements for operating upon each distinctly different part or a dented wheel-guard or the like; that is, on parts that have distinctly different normal curvatures or concavities and convexities, as where the curvatures are cycloidal or involute.

Another object is to provide an-improved type of hammer-head whose hammer-faces merge into a. non-hammering smooth pressing surface througha gradually diminishing difference between the maximum protrusion and the maximum depression 'of its operating or impinging surface.

Another object is to provide, in a kit for the purpose stated, a multi-faced rotary anvil of which, each of the faces has a different degree of curvature from that of the other faces, such faces being alternatively adaptable to different normal curvatures of the fender or wheel-guard or other curved sheet metal surface to be treated, so the finished work of repairing a dent in the sheet metal part will be at the maximum of smoothness and accuracy.

Other objects and important features are pointed out or implied in the following details of description, in connection with the accompanying drawing in which:

Fig. 1 is a side elevation of one form of my kink-repair kit in its useful relation with a dented wheel-guard in which the dent is simple or not compound, said wheel-guard being in vertical longitudinal section, a part of the flexible operating shaft being broken out.

Fig. 2 is a side elevation of a modified form of the kink-repair kit in its useful relation with a wheelguard in which the dent is compound, or both inwardly and outwardly or upwardly and downwardly bulged and correspondingly kinked or depressed.

Fig. 3 is an inner-side view of a four-bulge hammer-head that constitutes one element of my invention. I

Fig. 4 is an upper or outer-side view of the hammer-head shown in Fig. 3.

Fig. 5 is a central or radial sectional view of the hammer-head shown in Figs. 3 and 4.

Fig. 6 is an inner-side view of a three-bulge hammer-head as an element of my invention.

Fig. 7 is an inner-side view of a. two-bulge hammer-head as an element of my invention.

Fig. 8 is an inner-side view of a single-bulge hammer-head as an element of my invention.

Fig. 9 is a side view of one form of rotary anvil as an element of my invention.

Fig. 10 is a side view of another form of rotary anvil as an element of my invention.

- Fig. 11 is a sectional view of the anvil shown in Fig. 10, minus the handle and spindle, the section being along line I|H of Fig. 10.

Referring to the drawing indetail, wherein, similar reference numerals refer to similar parts in the several views, the invention is described in detail as follows:

Referring first tothe rotary hammer-head 20, it will be seen that it is a semi-globose unit that is practically concavo-convex, and is distinguished by having four bulges or radial protrusions alternating with radially depressed parts that form its periphery and converge towards the outer pole or outer axial point about which the unit rotates when in operation; but instead of these protrusions 2| and depressions 22 continuing to said pole they terminate in an even and smooth convexity 23; and it will be seen that the degree of protrusion or bulge is greatest at the periphery or outer margin, and is gradually decreased towards the part 23; also, that the depth of the depressions is greatest at. the outer margin, and is gradually decreased toward the smooth convexity 23. The inner or concave side of the unit power-applying shaft 28 which latter is preferably a flexible shaft and includes a power attaching end or coupling 21. The spindle 25 is suitably journaled in a tubular journal 28 and held against longitudinal movement therein by any appropriate means (not shown) while being rotatable at high speed therein by the power applied at 21 by any appropriate source (not shown). While it is possible to consider and use the journal 28 as a handle for applying the hammer head to the work, it is preferable and beneficial to provide and use a handle such as shown at 29, adjustably secured to the bearing or Journal 28 and projecting radially therefrom so as enable the user to apply the hammer-head with maximum ease, accuracy and regulated pressure to the work. while resisting torque of the journal 25.

The only distinction between the unit 20 of Figs. 1 to 5 and the unit 30 of Fig. 6 is that the latter has only three of the protrusions or bulges and corresponding depressions, and that these bulges are of greater arcuate extent, so are designated by the numeral 3|, and the depressed parts being designated 32.

While the radially bulged parts 33 and radially depressed parts 34, of Fig. '7, are less pronounced than those of the units 20 and 30, they may properly be distinguished by their respective maximums, that is, the maximum degree of 'bulge at 34; and the same as to Fig. 8 where the maximum bulge or radial protrusion is seen at 35, and the maximum radial depression is seen at 36.

In each of the rotary hammer-heads, in Figs. 1 to 8 inclusive, each radial protrusion and adjoining radial depression merges into an even and smooth convexity at the axial pole, as shown at 23 in 4; and in each of these forms of rotary hammer-head, the bulges are smooth and practically unbroken and constitute the multidirection convex hammer faces that constitute the major part of each of these units; for the depressed parts may be considered as confined to mere narrow lines that form the ends of the shortest radii from the axis of rotation. Therefore, it will be seen that the radii of the respective bulges are gradually varied in length from the shortest at the depressions to the longest at the maximum protrusion of the bulges. In the foregoing and in the claims, the term 'multidirection means that the convexity is like that of a globe-segment, as distinguished from the convexity of a cylinder or cone segment.

Now referring again to Figs. 1 and 2, where the simple dent is designated S and the compound dent is designated C. and where two anvils are seen at 31 and 38, it should be understood that any one of the rotary hammer-heads can be interchanged with the hammer-head 20 so as to be driven at a high speed of rotation while being held to the work by one hand of the user while the anvil may be held either by his other hand or by a helper; and either the operator or helper should judge (as nearly as possible) the degree of normal curvature of the part being repaired, thatis, the curvature that existed before the dent was made, hence, the degreeof curvature to which it is to be restored, and the curvature of the anvil's face should be chosen and applied to conform (as nearly as possible) to the said normal curvature, and held opposisite to the rotary hammer being operated. As the hammer-head is rotated while held against 'a boss, at opposite side from the dent, each complete rotation of the hammer-head delivers as many blows or impacts as the number of bulges or hammer-faces of the respective hammer-head; and, as better results are obtained by a large number of light impacts than by a few heavy impacts, either the hammer-head 20, or one having a larger number of bulges or hammer-faces may be preferable (in most cases) to a hammerhead such as shown in Fig. 6 or 7 or 8. While these hammer heads can be operated at high speeds to deliver impacts in rapid succession, they can also be operated at lower speed so as to deliver pushing impulses, and for such purpose, the devices shown in Figs. 7 and 8 may be preferable in most cases; but such pushing impulses can also be attained'by all these forms of hammer-head to a greater or less extent; for none of them have an abrupt striking face, being gradual from the depressed portions to the portions of maximum protrusion; so the sliding and pushing against the boss (opposite to the dent) always accompanies the striking or hammering action. While in operation, the hammer head should be, moved continually but gradually from place to place, and of course the anvil should be kept opposite to it, best results being usually obtained by working around the margin of the dent-boss, or back and forth along one edge thereof, until the finishing point is reached. However, each operator may use his own judgment as to details of operation.

In normalizing a compound dent it is necessary to have an anvil with a convex face, such as shown at 38, in Fig. 2, so as to fit it against the normal concave of the sheet metal member's dented part; and in such case, the rotary hammer is operated on the normally convex side until the dent is reduced to a simple (non-compound) state; whereupon, the elements of the kit are applied as in Fig. 1.

Instead of the forms of anvil shown in Figs. 1 and 2, I may employ the form; shown in Fig. 9 so it can be rolled from one point to another for keeping it opposite to the rotary hammer; or, so as to most nearly fit the different c'onvexities of a sheet metal object formed about cycloidal or involute lines, I provide the multi-concavity anvil of Figs. 10 and 11, in which it is seen that the curvatures of the cavities or concaves 38, 40, ll, 42, 43 and 44 have different degrees of curvature, each being generated about a radial center of a different radial distance therefrom than the radial distance of each of the others.

From the foregoing, it will be seen that the invention in general consists of all the interchangeable units here disclosed,'inasmuch as they are each useful in its turn for operating on a single dented part so as to normalize such part and thus accomplish a unitary result by the succession of functions performed thereby.

The invention also consists of or includes the novel form of hammer-head per se; or more properly, the novel type of hammer-head which is exemplified in all the different forms here shown; and it also includes the novel type of hammer-head in combination with its manipulative and power-transmitting adjuncts as shown tion to make them of other metals, alloys or even non-metallic materials; and the invention is susceptible of numerous changes of form and structure within the scope of the inventive ideas as herein implied and claimed.

What 1 claim as my invention is:

1. A rotary hammer-head comprising a onepiece semi-globose unit of hard material provided with an actuating side having axially disposed attaching means for connection with operating means to support it and efiect its rotation,

ripheral parts of said impinging side, for the purpose specified.

2. A rotary hammer-head comprising a semiglobose one-piece unit provided with an attaching side having axially disposed attaching means adapted for connection with means to support it and effect its rotation, the impinging side of said hammer-head being mainly convex and including smooth radially protruding convex hard portions alternating with peripheral depressed portions that extend towards an axially alined point and terminate in an unbroken and smooth convex area around said axially alined point, for purposes specified. FREDERICK TOOP. 

